Physiology of Ageing Flashcards
List 7 factors that are thought to contribute to the ageing process?
Overall due to an accumulation of cellular defects. The specific mechanisms are proposed to be as follows:
- Chromosome mutations
- Mitochondrial mutations
- Intracellular aggregates
- Extracellular aggregates
- Loss of stem cells and cell replacment
- Cell senescence (useless/harmful cells)
- Extracellular proteins
What is meant by frailty?
Loss of body homeostasis and resilience
Increased vulnerability to decompensation after a stressor event
Increased risk of falls delirium and disability
What are the two main scoring systems used to assess frailty and how do they work?
- Deficit accumulation (Rockwood)
- Takes a large number of body systems and counts how many of them have deficits (eg low walking speed, diabetes etc)
- The index of deficits is divided by the total number of systems to give a score between 0 and 1 - Phenotypic (Fried)
- 1 point for each of:
- Unintentional weight loss
- Low grip strength
- Self-reported exhaustion
- Low physical activity levels
- Slow walking speed
0 = non-frail
1-2 = pre-frail
3 or more = frail
What is a telomere?
The end part of each chromosome arm and consists of multiple repeats (usually TTAGGG) which form a loop. Its of variable length and progressively shortens with each cell replication. Eventually it becomes to short to sustain cell replication which leads to cell senescence. These are thought to provide a marker of biological age
What is telomerase?
A ribonucleoprotein that can re extend shortened telomeres. It is very active n cells that divide many times such as stem cells.
What is the purpose of telomeres?
To allow chromosome replication (DNA polymerase binds to here)
They also may provide a mechanism for stopping cells from replicating forever.
What disease are associated with shortened telomeres?
Anaemia, dementia, CVS disease
Is having shorter telomeres good or bad?
Bad. The shorter your telomeres are the sooner you will die
Give the three broad theories that try to explain ageing?
- Damage and dysfunction
- Extrinsic and intrinsic factors cause damage at a cellukar level
- Accumulation of this may lead directly to cell death via apoptosis but can also lead to mitochondrial dysfunction (may explain why muscle and nerve cells don’t work as well at advanced age) - Disposable soma
- Once reproductive age is over the body does not repair damage in the same way it used to. - Antagonistic Pleiotropy
- Genes that are beneficial early in life cause cell senescence and death in later years
Do you tend to lose strength in your upper or lower limbs first?
Lower
Why are muscles more prone to fatigue in later life?
Decrease in total muscle mass with ageing means that each unit of muscle tissue is responsible for the support and movement of a greater proportion of the total body mass - meaning it becomes tired more quickly
How is muscle strength in old people frequently measured in clinical practice?
Grip strength - isometric measurement
What device could you use to measure postural sway in a person?
Ataximeter
How does the residual volume change as we age?
Increases by up to 50% (this means that there is increases air remaining in the lungs after the most complete expiration possible for a person)
How does vital capacity change as we age?
Reduces - decreases ability to inhale hold exhale and breathe
